This invention relates to an electro luminescent element, specifically relates to an electroluminescent element useful in a civil or industrial displaying device such as a light-emission type multi- or full-color display, or a displaying panel, and color image forming method and a color filter (color conversion filter).
Electronic display device include a light-emission type and a light-receiving type. Examples of the light-emission type include a CRT (cathode ray tube), a PDP (plasma display), an ELD (electroluminescent display), a VFD (fluorescent display tube) and a LED (light-emitting diode).
Among them, the LED will be described below.
The LED is a light emission element comprising a light emission material emitting light in an electric field or combination of several number of such the element. The elements are classified into an organic element and an inorganic element according to the material and into a carrier injection type and an accelerated electron type according to the light emission mechanism. The recombination of an electron and a positive hole is utilized in the carrier injection type element and collision energy of an accelerated electron is utilized in the accelerated electron type element. Generally, the inorganic material is longer in the life time and more stable than the organic material. However, it is a shortcoming of the inorganic material that the choice of the material is narrow and there is a limitation on the molecular design thereof. The recombination type has advantage that the driving voltage is lower than that for the electron accelerate type. Recently, therefore, the carrier injection type LED is extensively developed.
The LED include the following three types.
(1) Inorganic LED comprising a inorganic compound such as GaN and GaInN: the light emission mechanism thereof is recombination type. It is simply called also as LED (light emission diode).
(2) Organic LED comprising an organic compound such as a triarylamine derivative and a stilbene derivative: the light emission mechanism thereof is recombination type. It is called as an organic EL (electroluminescent or OLED.
(3) Inorganic EL comprising an inorganic material such as ZnS:Mn and ZnS:Tb: the light emission mechanism is the accelerated electron type. It is called simply as an electroluminescent element since the element of such the type is historically old.
The xe2x80x9celectroluminescent materialxe2x80x9d in the invention includes the above-mentioned (1) and (2). Therefore, (3) is not subject of the invention.
In the field of the carrier-injection type organic electroluminescent element which has been particularly noted in recent years, ones emitting high luminance light have been becoming to be obtained after a thin layer of organic compound has been used. For example, U.S. Pat. No. 3,530,325 discloses one using a single crystal of anthracene as the light-emission substance, Japanese Patent Publication Open for Public Inspection (JP O.P.I.) No. 59-194393 discloses one having a combination of a positive hole injection layer and an organic light emission layer, JP O.P.I. No. 63-295695 discloses one having a combination of a positive hole injection layer and an organic electron injection layer, and Jpn. Journal of Applied Physics, Vol. 127, No. 2, p.p. 269-271, discloses one having a combination of a positive hole transportation layer and an electron transportation layer. The luminance of emission light is improved by such the means.
Besides, a fluorescent substance has been known, which emits fluorescent light by absorbing light emitted from the electroluminescent material. The method using such the fluorescent substance to emit various colors light by means of an electroluminescent material is applied for the CRT, PDP, VFD, etc. However, in such the case, there is a problem that light emitted from the electroluminescent material must be a high energy ray (i.e., short wavelength emission),such as an electron ray or a far ultraviolet ray. The fluorescent substances described above are essentially inorganic fluorescent substances. There are known a number of the inorganic fluorescent substances which are superior in stability, exhibiting long shelf-life. However, there has not been found a long wavelength excitation type inorganic fluorescent substance exhibiting an excitation wavelength in the region of near ultraviolet to visible light, specifically, red light.
A near ultraviolet ray capable of being emitted from the electroluminescent material is contemplated to be a light having a peak of wavelength within the range of from approximately 350 nm to 400 nm, and the use of an organic fluorescent dye as the fluorescent substance capable of excited such the near ultraviolet ray is disclosed in JP O.P.I. Nos. 3-152897, 9-245511 and 5-258860.
However, it is known that the organic fluorescent dye is generally tends to be influenced by the circumstance condition, for example, change in the wavelength or quenching tends to be occurred depending on the kind of solvent or medium such as a resin.
In the methods disclosed in the foregoing publications, a fluorescent dye absorbs light of blue or blue-green light region emitted from the electroluminescent material and converts the light to red light. A fluorescent conversion layer which emits light in green region has characteristics that the Stokes shift (the difference between the wavelength of the absorbed light and that of the emitted light) is small, and a part of light emitted from the electroluminescent material can be permeated therethrough, and the light from the light emission material can be converted with a relative high efficiency. However, the conversion to the fluorescent to light of red region caused problems that the conversion efficiency is considerably low since a large Stokes shift is needed and the light from the light emitting material almost cannot be utilized. Exemplarily, the combined use of a few fluorescent dyes different in excitation wavelength is needed and it is necessary to utilize light-to-light conversion (i.e., photoluminescence) of plural fluorescent dyes, such as a fluorescent dye emitting yellow light in response to blue light and a fluorescent dye emitting red light in response to yellow light.
Accordingly, there is a problem that the visual perceivability and the luminance of color displaying by such the element are lowered since the luminance balance between blue, green and red light emission is unsuitable and the above-mentioned quenching and decoloration are occurred.
The inventors can obtain an electroluminescent element capable of emitting a high luminance light and having a high storage ability, and can provide a color filter with a high luminance by the use of such the electroluminescent element.
The above-mentioned object of the invention can be attained by the following constitution:
(1) An electroluminescent material represented by the following Formula N1: 
wherein Ar is an aryl group; A is a carbon atom, a nitrogen atom, a sulfur atom or an oxygen atom; X is a group of atoms necessary to form a 5- or 6-member nitrogen containing aromatic heterocyclic ring together with A and N; Y is a group of atoms necessary to form a 5- or 6-member aromatic hydrocarbon or aromatic heterocyclic ring; the bond of Cxe2x80x94N, Cxe2x80x94A or Cxe2x80x94C in the formula is a single or double bond; and R is a hydrogen atom, a substituent or Ar; provided that the nitrogen-containing aromatic heterocyclic ring represented by 
and the aromatic hydrocarbon ring or the aromatic heterocyclic ring represented by 
each may be condensed with a hydrocarbon ring or a heterocyclic ring.
(2) An electroluminescent material represented by the following Formula A1: 
wherein Ar11, Ar12 and Ar13 are each an aryl group or an aromatic heterocyclic group, and a biaryl group having a bond capable of giving at least two internal rotational isomerism is in the molecule of the compound represented by Formula A1.
(3) An electroluminescent material represented by the following Formula A2: 
wherein Ar21, Ar22 and Ar23 are each an aryl group or an aromatic heterocyclic group, each of which has a bond exhibiting C2 rotation symmetry and capable of giving an internal rotational isomerism.
(4) An electroluminescent material represented by the following Formula A3: 
wherein Ar31, Ar32 and Ar33 are each an aryl group or an aromatic heterocyclic group, provided that at least two of Ar31, Ar32 and Ar33 are each an aryl group having a 1,1xe2x80x2-binaphthyl moiety.
(5) An electroluminescent material represented by the following Formula B1, 
wherein Ar41 and Ar42 are each independently an aryl group or an aromatic heterocyclic group; L11, L12 and L13 is each a group of atoms necessary to form an aromatic heterocyclic ring, provided that at least one of L11, L12 and L13 is xe2x95x90Nxe2x80x94, xe2x80x94N(R41)xe2x80x94, xe2x80x94Sxe2x80x94 or xe2x80x94Oxe2x80x94; R41 is a hydrogen atom or a substituent, provided that at least-one of Ar41, Ar42 and R41 is a biaryl group having a bonding axis capable of giving an internal rotational isomerism or a group having such a biaryl group, and the adjacent substituents may be condensed with each other to form a saturated or unsaturated ring.
(6) An electroluminescent material represented by the following Formula C1, 
wherein Ar51 is an aryl group or an aromatic heterocyclic group; n is an integer of from 0 to 6, the plural groups represented by Ar51 may be the same or different when n is 2 or more; L21, L22, L23, L24, L25 and L26 are a group of atoms necessary to form a 6-member nitrogen-containing aromatic heterocyclic group, provided that at least one of L21, L22, L23, L24, L25, and L26 is xe2x95x90Nxe2x80x94, or xe2x80x94N(R51)xe2x80x94; R51 is a hydrogen atom or a substituent, provided that at least one of Ar51 and R51 is a biaryl group having a bonding axis capable of giving a internal rotation isomerism or a group having such a biaryl group, and the adjacent substituents may be condensed with each other to form a saturated or unsaturated ring.
(7) An electroluminescent material represented by the following Formula D1, 
wherein Ar61 and Ar62 are each an aryl group or an aromatic heterocyclic group; R61 and R62 are each a hydrogen atom or a substituent, provided that at least one of Ar61, Ar62, R61 and R62 is a biaryl group having a bonding axis capable of giving a internal rotational isomerism or a group having such a biaryl group, and the adjacent substituents may be condensed with each other to form a saturated or unsaturated ring.
(8) An electroluminescent material represented by the following Formula E1,
Mnxe2x80x2+(L71xe2x88x92)m(R71xe2x88x92)nxe2x80x2xe2x88x92mxe2x80x83xe2x80x83Formula E1
wherein M is a metal atom capable of taking an ionized state of from 1- to 4-valent (i.e., giving 1- to 4-valent ions); nxe2x80x2 is a natural number of from 1 to 4; L71xe2x88x92 is a monovalent anion capable of forming an ionic bonding with M and having a portion capable of coordinating with M; m is a natural number of the same as nxe2x80x2 or less; R71xe2x88x92 is a monovalent anion capable of forming an ionic bond with M, provided that at least one of L71xe2x88x92 and R71xe2x88x92 is a group having a moiety of biaryl group having a bonding axis capable of giving an internal rotational isomerism.
(9) An electroluminescent material represented by the following Formula F1 or F2, 
wherein Z1 and Z2 are each independently a monovalent residue of a light emitting compound; Z3 is a k-valent residue of a light emitting compound; k is a natural number of from 1 to 8, x is a natural number of from 1 to 3; y is an integer of from 0 to 3, provided that plural groups represented by Z1 may be the same or different when x is 2 or more, plural groups represented by Z2 may be the same or different when y is 2 or more, and groups represented by Z1 and Z2 may be the same or different when both of x and y are each 1 or more; R81 and R82 are each independently a substituent, n is an integer of from 0 to 4, m is an integer of from 0 to 4, provided that plural groups represented by R81 may be the same or different and may be condensed with each other to form a ring when n is 2 or more, plural groups represented by R82 may be the same or different and may be condensed with each other to form a ring when m is 2 or more, and R81 and R82 may be the same or different when both of n and m are 1 or more. The substituent of each of Z1, Z2, R81 and R82 may form a condensed ring with the naphthalene ring.
(10) An electroluminescent material which is prepared using a 4-halo-1,1xe2x80x2-binaphthyl derivative represented by Formula G1 as raw material and has a monovalent biaryl group represented by Formula G2 in the molecule of the material: 
wherein X91 is a halogen atom; R91 and R92 are each a substituent; n is an integer of 0 to 4; and m is an integer of 0 to 4, provided that when n is 2 or more, plural R91s may be the same or different, or condensed with each other, when m is 2 or more, plural R92s may be the same or different, or condensed with each other, and when n and m are both 1 or more, R91 and R92 may be the same or different.
(11) An electroluminescent element comprising an electroluminescent material and an inorganic fluorescent substance which absorbs light emitted from the electroluminescent material and fluoresces at the maximum emission wavelength different from that of light emitted from the electroluminescent material.
(12) The electroluminescent element described in (11), wherein the inorganic fluorescent substance is an inorganic fluorescent substance prepared by a Sol-Gel method.
(13) The electroluminescent element described in (11) or (12), in which the inorganic fluorescent substance emits light having the maximum emission wavelength of from 400 nm to 700 nm.
(14) The electroluminescent element described in any one of from (11) to (13), wherein at least one of the inorganic fluorescent substance emits light having the maximum fluorescence wavelength of from 600 nm to 700 nm.
(15) An electroluminescent element which comprises an electroluminescent material and a rare earth metal complex fluorescent substance which absorbs light emitted from the electroluminescent material and fluoresces at the maximum wavelength different from that of the light emitted from the electroluminescent material.
(16) The electroluminescent element described in (15), wherein the maximum emission wavelength of light emitted from the rare-earth metal complex fluorescent substance is within the range of from 400 nm to 700 nm.
(17) The electroluminescent element described in (15) or (16), wherein the maximum emission wavelength of light emitted from the rare-earth metal complex fluorescent substance is within the range of from 600 nm to 700 nm.
(18) The electroluminescent element described in any one of (11) to (17), wherein the maximum emission wavelength of light emitted from the electroluminescent material is not more than 430 nm.
(19) The electroluminescent element described in (18), wherein the maximum emission wavelength of light emitted from the electroluminescent material is within the range of from 400 nm to 430 nm.
(20) The electroluminescent element described in any one of (11) to (19), wherein the electroluminescent material is an organic LED material.
(21) The electroluminescent element described in any one of (11) to (19) wherein the electroluminescent material is an inorganic LED material.
(22) The electroluminescent element described in any one of (11) to (21), wherein the electroluminescent material is a compound selected from the group consisting of compounds represented by Formula N1, A1, A2, A3, B1, C1, D1, E1, F1 or F2, as described in (1) to (9) or a compound as described in (10).
(23) An electroluminescent element comprising a substrate, provided thereon, a layer containing at least an electroluminescent material and a color conversion layer, wherein the color conversion layer contains an inorganic fluorescent substance which absorbs light emitted from the electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 500 nm, an inorganic fluorescent substance emits light having the maximum emission wavelength of from 501 nm to 600 nm, and an inorganic fluorescent substance emits light having the maximum emission wavelength of from 601 nm to 700 nm.
(24) An electroluminescent element comprising a substrate, provided thereon, a layer containing an electroluminescent material and a color conversion layer, wherein the color conversion layer contains a rare earth metal complex fluorescent substance which absorbs light emitted from the electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 500 nm, a rare earth metal complex fluorescent substance emits light having the maximum emission wavelength of from 501 nm to 600 nm, and a rare earth metal complex fluorescent substance emits light having the maximum emission wavelength of from 601 nm to 700 nm.
(25) A color conversion filter which contains at least an inorganic fluorescent substance which absorbs light emitted from an electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 700 nm.
(26) A color conversion filter which contains an inorganic fluorescent substance which absorbs light emitted from an electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 500 nm, an inorganic fluorescent substance emitting light having the maximum emission wavelength of from 501 nm to 600 nm, and an inorganic fluorescent substance emitting light having the maximum emission wavelength of from 601 nm to 700 nm.
(27) The color conversion filter described in (24) or (25) wherein at least one of the inorganic fluorescent substance is one prepared by a Sol-Gel method.
(28) A color conversion filter which contains at least an rare earth metal complex fluorescent substance which absorbs light emitted from an electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 700 nm.
(29) A color conversion filter which contains a rare earth metal complex fluorescent substance which absorbs light emitted from an electroluminescent material and emits light having the maximum emission wavelength of from 400 nm to 500 nm, a rare earth metal complex fluorescent substance emitting light having the maximum emission wavelength of from 501 nm to 600 nm, and a rare earth metal complex fluorescent substance emitting light having the maximum emission wavelength of from 601 nm to 700 nm.
(30) A color conversion method, comprising conversion of a light in a wavelength region shorter than a red light to the red light using an inorganic fluorescent substance which has been prepared by a sol-gel method.
(31) A color conversion method, comprising conversion of a light in a wavelength region shorter than a red light to the red light using a rare earth metal fluorescent substance.
(32) The color conversion method described in (31), wherein the rare earth metal complex has the maximum absorption wavelength of not less than 340 nm.
(33) A rare earth metal complex fluorescent substance containing at least an anionic ligand represented by the following formula R2: 
wherein R101 is a hydrogen atom or a substituent; Y101 is an oxygen atom, a sulfur atom or xe2x80x94N(R102), in which R102 is a hydrogen atom or a substituent; Z101 is a group of atoms necessary to form a 4- to 8-membered ring together with a carbon-carbon double bond.